For DVD delivery, export from FCP as a QuickTime self-contained or reference movie (File->Export->QuickTime Movie) - do NOT use QuickTime Conversion.

Import the resulting file into Compressor where you will choose a DVD preset based on the duration time of your program. Compressor will produce two files: an MPEG-2 video file (.m2v) and a Dolby Digital audio file (.ac3).

Import the two files produced by Compressor into a DVD Studio Pro project for authoring and burning.